Real-world programming (typically called real-time programming) is programming that interacts in some way with the "real world" of daily life. Real-world programmers develop the unseen software that operates most of the world that surrounds you, software typically characterized by deadlines -- and harsh penalties if the deadlines aren't met. When you've just rear-ended another car, it's no consolation that a sudden flurry of input slowed down your brake processor, so it couldn't react quickly enough when you hit the pedal. This book covers the POSIX.4 standard for portable real-time programming. The POSIX.4 standard itself is a massive document that defines system interfaces for asynchronous I/O, scheduling, communications, and other facilities. However, this book does more than explain the standard. It provides a general introduction to real-time programming and real-time issues: the problems software faces when it needs to interact with the real world and how to solve them. If you're at all interested in real-time applications -- which include just about everything from telemetry to transaction processing -- this book will be an essential reference. Includes problem sets, answers, and reference manual pages for all functions and header files.